New research shows that yeast, the most common form of waste from alcohol, can even filter out lead.
Inactive yeast can act as an inexpensive, dense, and simple substance to remove lead contamination from drinking water, according to a new scientific analysis at MIT’s Center for Bits and Atoms (CBA). Studies show that this method of operation can be effective and economical, even for half a billion dollars of waste. Significant damage to human health is known to occur even in these lower stages.
The approach is convenient. A team of researchers calculated that the amount of waste dumped in one Boston area would be sufficient to treat all city water. Such a fully sustainable system will not only clean the water but also respond to what would otherwise be a stream that needs to be disposed of.
The findings are described in detail in the journal Nature Communications Earth and Environment, in the paper by MIT Research Scientist Patritsia Statathou; Post University of Brown University and MIT Visiting Scholar Christos Athanasiou; MIT Professor Neil Gershenfeld, director of CBA; and nine others at MIT, Brown, Wellesley College, Nanyang Technological University, and the National Technical University of Athens. They were published on June 13, 2022.
Lead and other heavy metals in the water are a major global problem that continues to grow due to electronic waste and mineral emissions. In the U.S. only, more than 12,000 miles of waterways are affected by acidic water in mineral-rich metals, the world’s leading source of water pollution. And unlike biological pollutants, many of which could eventually be demolished, heavy metals do not degrade by biodegrading but persist permanently and accumulate. It is not possible or expensive to remove them entirely by conventional means such as chemical rain or membrane filters.
Lead is highly toxic, even when concentrated in small amounts, significantly affecting children as they grow older. The European Union has reduced its level of lead in drinking water from 10 parts per billion to 5 billion each. In the U.S., the Environmental Protection Agency has declared that no water level is safe. And standard groundwater levels are ten times higher than in the previous 50 years, from 10 billion per billion in Europe to hundreds of parts per billion in South America.
“We don’t just need to reduce lead; we need to get rid of it in drinking water,” said Stathatou. “And the fact is that conventional therapies do not do this effectively when the initial focus they have to take is low, on a per-billion scale and below. They may not be able to eradicate the numbers, or they may have to use a lot of energy and produce toxic substances.”
The solution learned by the MIT team is not new – a process called biosorption, in which organic matter is used to remove heavy metals from water has been known for decades. But the process has been tested and seen only at very high altitudes, at a rate of more than one-half million. “Our research shows that this process can be most effective in very low-lying areas of real-world water supply, and it investigates the processes involved in this process,” Athanasiou said.
The team explored a type of yeast widely used in alcohol production and industrial processes, called S. cerevisiae, in clear water with a small amount of lead. They have shown that one gram of inactive, dried yeast cells can dissolve 12 milligrams of lead in aqueous solutions by concentrating the lead in less than one-half per million. They also show that the process is speedy, taking less than five minutes to complete.